Power transmission



y 14, 1940- v E. A. THOMPSON 2200,81]

' PQWER TRANSMISSION Filed April -l, 1936 16 o g i .L

INVENTOR flown A. THOMPSON ATTORNEY Patented May 14, 1940 UNITED STATES POV WER TRANSMISSIQN Edward A. Thompson, Waterbury, Conn., as-

lignor to The Waterbury Tool C mp y,

Waterbury, Coma, a corporation of Connecticut Application April 1, 1936, Serial No. 12,108

, comm.

This invention relates to power transmissions, particularly to transmissions of the fluid type comprising a pump unit and a fluid motor unit; at leastone of which is provided with means for 6' varying its displacement wherebythe speed and torque ratios of the power transmissions may be smoothly varied. The invention is particularly adapted for use with a reeling device and has been illustrated as applied to a mechanism of this character although it will be understood that the invention is equally adaptable to other applications. In reeling devices wherein a strip of material is wound upon an arbor in successive layers, the diameter of the reeled material progressively increases as the material is wound on the reel. If the material is fed to the reel at a constant speed. the speed of the the tension or lack of tension maintained in the stripmaterial between the reel and the device which feeds the strip to the reel.

It is an object of the present invention to provide a power transmission and control therefor which will operate to maintain a constant 5 tension on the material being reeled and maintain a constant peripheral speed on the reeled material automatically in accordance with the' load on the power transmission,

A further object is to provide a control device for a variable speed power transmission whereby the output speed of the transmission is varied automatically to produce a constant horsepower at varying torques. Further objects and advantages of the present invention will be apparentfrom the following description, reference being had to the accompanying drawing wherein a preferred form oi the present invention is clearly shown.

In the drawing: g

'I'lg. l is a plan view of a power transmission and reeling device embodying a preferred form of the present invention.

Fig. 2 is auction. on line 2-2 of Fig. 1. In the form of the invention illustrated in Fig. 1 a reel i2 is provided -for windingstrip I material II on the arbor thereof. The strip material is fed to the reel from a feeding device which is illustrated as a slitting shear M. The feeding device" I4 is driven by a suitable prime Umnvcr. for example a variable speed electric motor. it through a reduction gear I8. The motor it also drives a fluid pump it which is of fixed displacement and is fllustrated as of the well-known fWaterbury"type. The pump it is connected by means of supply and return con- 5 'the axis of the motor to vary the piston stroke and consequently the displacement of the motor. The range of movement of the tilting box is limited by suitable stops. not shown. between a maximum displacement corresponding to the displacement of the pump it and a minimum displacement which is somewhat short of neutral or zero displacement. The tilting box 34 is operated by a pressure control comprising a stem 36 which carries a piston 38 slidable in a cylinder 40, the latter being in communication with the supply line 28 through a conduit 42.- 26 The stem 36 at its upper end carries a spring plate 44 against which the lower end of a spring 48 abuts. The upper end of the spring 56 abuts a spring plate 68 which is adjustable by means of a screw shaft w and control wheel 52.

In operation of the device a strip of material is fed through the feeding device with its end adjacent the arbor of the reel it and the end of the strip is suitably fastened to the arbor by a clamping device, not shown.

During this operation the arbor of the reel ill may be rotated backward if necessary by operating the reverse valve 24 to connect the supply conduit 20 to the conduit 28 which is the return T conduit in normal operation, the motor 88 be-. 40 ing inched" for this purpose. With the motor IB stationary the reverse valve is then shifted to normal operation in which the supply conduit 20 is connected to the conduit 26 and the return conduit 22 is connected with the conduit 45 28. The'motor it is then brought up to speed and the strip material it? is wound on the reel it. The spring it tends to urge the tilting box Q4 into the minimum displacement positionwhich tendency is counteracted by pressure err- 9 isting in the supply conduits 28 and 26.

At the instant the device is started the tension in the strip material i2 is below normal operating value so that as a result the fluid pressure in conduit 28 is low and the'spring 46 maintains the tilting box 36 in minimum displacement position. The fluid motor 20 therefore operates the reel at the highest possible's'peed immediately after starting until the tension in the strip i2 reaches the normal operating value at increased to keep the peripheral speed of the reel at a substantially constant value and to maintain the tension on the strip l2 likewise constant. As soon as the required amount of material is wound on the reel ill, the motor I6 is stopped and the web material cut so that the roll of reeled material may be removed and the reeling cycle is repeated,

It will be noted that the speed of the reel arbor is varied inversely to the change in torque thereon, as the lever arm of the tension force of the strip l2 increases; and that the power operating the reel III is therefore maintained constant. Viewed in another light the speed and displacement of the pump l9 are maintained constant and since the displacement of the motor is varied to maintain a constant working pressure in the conduits and 26, the power input to the pump is therefore likewise maintained constant. Small departures from these theoretically constant conditions are of course introduced due to the varying efliciency of the power transmission at different speeds and due to variations in force exerted by the spring 46 under different degrees of compression. These variations may be made small, however, and for practical purposes may be considered negligible.

While the form of embodiment of the invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope ofthe claims which follow.

What is claimed is as follows:

1. A device for reeling strip material comprising in combination a reel, driving means for the feel including a constant delivery fluid pump and a fluid motor driven by the pump, fluid conduits forming supply and return connections between the pump and motor the total resistance of said connections being negligible, and control means for maintaining a constant peripheral tension in the material being reeled includlng'means responsive to the fluid pressure developed by the motor in the supply connection for varying the displacement of the motor, said conduits being 3 arranged to deliver to the motor the full discharge of the pump under all normal conditions of operation.

2. A device for reeling strip material comprising in combination, a reel, feeding means for the reel, a fixed displacement fluid pump driven at a speed, the ratio of which is constant with respect to the speed of the feeding means, a fluid motor driven by the pump and connected to drive 'the reel, fluid conduits forming supply and return connections between the pump and motor the total resistance of said connections being negligible, and control means for maintaining a constant tension on the material between the reel and the feeding means, including-means responsive tov fluid pressure in the supply connection for decreasing the speed of the motor as the diameter of the reeled .material increases. 3. In a fluid power transmission the combinaspect to the speed of the feeding means, a fluid tion of a fixed displacement fluid pump, means for driving the pump at a substantially constant speed for delivering fluid at a uniform rate, a variable displacement fluid motor, fluid conduits forming supply and-return connections between the pump and motor the total resistance of said connections being negligible, and means responsive to pressure in the supply connection for regulating the displacement of the motor to maintain a substantially constant power output at varying motor speeds and loads.

4. Aidevice for reeling strip material compr ing in combination, a reel, means for feeding strip material to the reel, a constant delivery fluid pump unit, a prime mover for driving. both the pump and the feeding means, a fluid motor unit 'operated by the pump, fluid conduits forming strip material to the reel, a flxed displacement fluid pump, a prime mover for driving both the pump and the feeding means, a variable displacement fluid motor operated by the pump, and

means for varying the motor displacement to maintain constant fluid pressure on the pump,

whereby the tension on the material being reeled is maintained constant, and means including a valve for at times reversing the operation of the reel.

6. A device for reeling strip material comprising in combination, a reel, means for feeding strip material to the reel, a fixed displacement fluid pump, a prime mover for driving both the pump and the feeding means, a variable displacement fluid motor operated by the pump, fluid conduits forming supply and return connections between the pump and motor, the total' resistance of said connections being negligible, and means for varying the motor displacement to maintain constant fluid pressure on the motor, said means including a'seccnd fluid motor for varying the displacement of the first fluidmotor and means responsive to changes in fluid pressure developed in said supply connection for causing said second fluid motor to vary the displacement of the first fluid motor in a manner to restore said pressure to a predetermined sub-' stantially constant value, whereby the tension on the material being reeled is maintained constant.

7. A device for reeling strip material comprising in combination, a reel, feeding means for the reel, a fixed displacement fluid pump driven at a speed, the ratio of which is constant with re-- motor driven by the pump and connected to drive the reel, fluid conduits of negligible resistance forming supply and return connections between' D the pump and motor the totallreslstance of said connections being negligible, and control means for maintaining a constant tension on the material between the reel and the feeding means, ineluding means responsive to fluid pressure in the supplyccnnection for increasing the displacement of: the motor as the diameter of the reeled material increases.

onward: a. Thomson. I 

